Do they make a nest?

No, bats only use what is already there – caves, holes in trees, gaps in bridges, roofs of buildings, external features of buildings eg. behind fascia boards (a favourite roost site for pipistrelle bats). They do not make existing gaps bigger, they don’t chew cables in roofs, and they do not bring any nesting material into the roost with them. Bats need different conditions depending on the time of year. In summer female bats gather together to form nursery roosts. To enable the young bats to develop quickly they need a warm site such as a south facing gable or a roof space. Once the young are able to fend for themselves they choose cooler sites to enable them to conserve energy by slowing down their metabolism. In winter they need cool sites with high humidity. Winter sites include caves, tunnels and old mine workings.